Sea Level Rise.
Sea Levels are starting to rise around the globe. As the earth warms, glaciers and ice sheets melt, releasing water that had been locked up into the oceans. In addition as the water warms it expands also adding to the problem. Most of the world√?¬?s largest cities containing millions of people lie at or very close to sea level. The Greenland Ice sheet contains enough freshwater to raise global sea levels by 5 metres, it is currently melting at an alarmingly rapid rate. It seems likely that in the next 30-50 years, millions of people will be made homeless. Tuvalu lying at or barely above sea level will probably one of the first countries to disappear due to global warming.